The present invention relates generally to methods and apparatus for forming and handling membranes.
Membranes, such as elastomeric membranes, have been used in micro-fabrication processes to pattern materials (e.g., electro-luminescent material) on a substrate. One such process is described in detail in Duffy et al., xe2x80x9cPatterning Electroluminescent Materials with Feature Sizes as Small as 5 xcexcm Using Elastomeric Membranes as Masks for Dry Lift-Offxe2x80x9d, Advanced Materials, 11, No. 7 (1999) 546-552. Another micro-fabrication process which employs membranes is the use of elastomeric lift-off membranes for the patterning of proteins and cells onto the surfaces of bacteriological Petri dishes, glass, etc. as described, for example, in Ostuni et al., xe2x80x9cPatterning Mammalian Cells Using Elastomeric Membranesxe2x80x9d, Langmuir, Jun. 21, 2000. Still another micro-fabrication process is the use of membranes as masks in dry-lift off to produce patterned features of materials such as metals, sol-gels, hydrogels, biological macromolecules and organometallic molecules, such as described in Jackman et al., xe2x80x9cUsing Elastomeric Membranes as Dry Resists and for Dry Lift-Offxe2x80x9d, Langmuir 1999, 15, 2973-2984 (Jan. 14, 1999).
Membranes, such as elastomeric membranes, may be fabricated by molding the membrane material using a master mold having a mold pattern that can impart the desired shape to the membrane during molding. For example, in one membrane fabrication process, a pre-determined pattern of photoresist posts is formed on a wafer (e.g.xe2x80x94silicon) using, for example, a process such as photolithography. The elastomeric membrane, or mask, is then created by applying a membrane material to the master that acts as a mold so that, when cured, the membrane has a shape with indentations or through-holes corresponding to the locations of the photoresist posts.
Many applications require very thin membranesxe2x80x94some on the order of 3 microns or less. Membranes that have such small thicknesses are often extremely difficult to handle. For instance, in order to peel such a thin membrane from the master mold, a user may use a microscope to aid in grasping an outer portion of the membrane with a pair of tweezers. To facilitate the removal of the membrane from the master, the user may also apply a solvent, such as ethanol.
However, this grasping may result in tears or other damage. Furthermore, the elastomeric material which comprises the membrane may be very adherent to itself. Thus, the membrane often folds when being handled, and when two surfaces of the membrane contact each other, it is very difficult to separate the surfaces without doing permanent damage to the membrane. However, these very thin membranes have commonly been made in sizes which fit, for example, in a standard Petri dish (approximately 3 inches in diameter). The small surface area of these thin membranes may help to reduce the severity of these problems.
The present invention, according to one example embodiment thereof, is directed to a handling method for forming a membrane. According to the method, a coating of membrane material on a substrate and a support member are brought into contact. The membrane material is cured so as to form the membrane and to bond the support member to the membrane. The support member has a rigidity that is greater than the membrane, such that, when the support member is bonded to the membrane, the support member maintains at least a portion of the membrane in a substantially taut condition to prevent a portion of the membrane from tearing or folding onto itself.